The diamond-like carbon film (DLC film) has a hard, fine and inert surface. Therefore, when formed on the surface of a material, for example, an inorganic material, such as a metal, ceramic, etc., or an organic material, such as a resin, etc., the DLC film can give the surface of the material certain characteristics, such as abrasion resistance, corrosion resistance, surface smoothness, etc.
For example, it has been known that coating the surface of a mold or tool with a DLC film improves the durability and releasability. Further, the coating creates a very smooth and inert surface and therefore has been a promising surface treatment for materials of medical instruments which should not cause interactions with biosubstances (see, for example, Patent Document 1 and Non-Patent Document 1).
Meanwhile, modifying the surface of a material with various substances to achieve high functionality on the material surface has been studied. With this, for example, development of nanodevices for molecular recognition on a semiconductor surface modified with functionality components, development of antithrombotic medical materials where the surface of the materials is modified with an antithrombotic material.
Various studies have been conducted especially on the means for providing biocompatibility, such as antithrombogenicity, etc., to the surface of a medical material. For example, it has been known that a hydrogel layer similar to the surface of a biomembrane can be formed on the surface of a medical material by modifying the surface of the medical material with a polymer containing as one component an artificial material having a chemical structure similar to the components of the biomembrane, such as 2-methacryloyl-oxyethyl phosphorylcholine (MPC), o-methacryloyl-L-Serine (SerMA), or the like, whereby excellent biocompatibility can be given to the surface of the medical material.
The surface of the material which is to be modified by such a functionality component is preferably refractory and inert. When the material surface has high reactivity, there is a possibility that an interaction between the material surface and a functionality molecule as a modifier denatures and deactivates the modifier functionality component. Further, certain environments degrade the material itself. Therefore, a material coated with a very smooth, inert DLC film is expected to exhibit excellent quality as a material which is to be modified with a functionality component, etc.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 10-248923
[Non-Patent Document 1] Haruo Ito et al., “Biomaterial”, 1985, Vol. 3, pp. 45-53